However, a spokesman for the retailer said that it will inform the Irish data office that no Irish customers were affected by the breach.

The spokesman told the Irish Independent that the retailer saw no systems potentially compromised by the data breach.

Carphone Warehouse has 90 stores in Ireland and is expected to launch its own mobile operator, iD Mobile, here before the end of the month.

The spokesman said that Irish customers who have signed up to register their names, email addresses and phone numbers with iD Mobile in advance of its launch "are not affected".

He said the new mobile operator uses "completely separate" IT systems to its sister network in the UK.

The company said some iD Mobile users in the UK could have had their personal details compromised in the breach.

A spokesman for the Office of the Irish Data Protection Commissioner, Helen Dixon, said that it has not yet received any communication from Carphone Warehouse or iD Mobile regarding the data breach. In the UK, Carphone Warehouse said the "sophisticated cyber attack" was stopped "straight away" after its own systems discovered it last Wednesday afternoon.

Asked when the data breach began, a spokesman replied: "the evidence indicates within the last two weeks (before Wednesday)".

The company has warned that the encrypted credit-card information of up to 90,000 people in the UK may have been accessed during the attack.

A spokesman for the retailer said additional security measures have since been put in place.